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This invention, entitled Variable Inductance Transducer Circuit Producing an Electrical Current and Voltage Output, was devised and invented by Douglas H. Beyer, and relates to a new and useful type of displacement transducer that utilizes inductance changes in a transducer circuit to effect a transducer output signal, representing one or more of the following: a displacement measurement, a change in magnetic field permeability, a change in reluctance in a magnetic field, an inductance change in a deformable coil, an eddy current effect, a magnetic saturation, or other effects based on a change of inductance. Throughout this specification and its appended claims, the present invention will be referred to as the proper noun: xe2x80x9cInductive Displacement Transducerxe2x80x9d or the xe2x80x9cTransducerxe2x80x9d.
The term xe2x80x9ctransducerxe2x80x9d as used throughout this specification and its appended claims is intended to refer to a device to convert a physical effect or property to a signal or the like, said signal generally being electrical, but may also be electromagnetic, e.g., radio frequency, microwave, optical, infrared or fiber optic.
The term xe2x80x9ccurrentxe2x80x9d as used throughout this specification and its appended claims is intended to refer to either a pulsed or a time averaged current.
The term xe2x80x9ccircuitxe2x80x9d as used throughout this specification and its appended claims is intended to refer to a complete circuit, or to a subset or subsection thereof, comprised of a device or set of devices, identified as performing specified functions.
The term xe2x80x9cinductancexe2x80x9d as used throughout this specification and its appended claims, is intended to refer to the property of a component to oppose a change in current, this property being related to the magnetic or electromagnetic field produced by the current.
The term xe2x80x9ccomparatorxe2x80x9d as used throughout this specification and its appended claims is also intended to refer to any equivalent device such as a differential voltage comparator, operational amplifier (xe2x80x9cop-ampxe2x80x9d), Schmitt trigger, differential transistor pair, one or more transistors referenced to a voltage that determines the xe2x80x9conxe2x80x9d or xe2x80x9coffxe2x80x9d state(s).
This invention relates to the field of displacement transducers that are generally designed and manufactured by the sensor industry and have application in a variety of industries, such as medical electronics, electronic music, manufacturing and process control, hydraulic equipment, aircraft and vehicle industries.
Heretofore, inductance type displacement transducers have largely used linear or rotary variable differential transformer means or a Hall effect detection of magnetic change, to convert a displacement or angular measurement to an electronic or electromagnetic signal. The inductance-based displacement transducers previous to the herein disclosed invention have been more expensive to manufacture and required more complex electronic circuitry to transduce a signal. Since sensors based on inductance change offer several potential advantages for high temperature operation, non-contacting measurement means, and tolerance to harsh environments, it is desirable to improve and simplify the electronics required to extract a useful signal from a change in inductance.
In trying to solve the above-described transducer industry problems and disadvantages, and within the scope of this invention, the inventor, Douglas H. Beyer, has devised and invented a new and useful type of displacement transducer, that utilizes the disclosed evaluation circuit to realize the advantages of inductance-based displacement measurements. The advantages of the Inductive Displacement Transducer circuits disclosed herein follow. The Inductive Displacement Transducer may be designed to allow single or multiple inductance change measurement capability, as shown in FIG. 10. The Inductive Displacement Transducer may be utilized to affect broader media and environmental compatibility, and may be more easily adapted to equipment exposed to continuous use and to harsh environments. The Inductive Displacement Transducer is simpler in design, and may be manufactured at high quality control standards at a lower cost. The Inductive Displacement Transducer offers compatibility to a greater range of inductance values and inductor types, and therefore may be manufactured with a smaller size than transducers that are presently available, and this smaller size will permit the manufacture of more efficient devices, more portable devices, and less expensive transducer devices. The Inductive Displacement Transducer is easier to manufacture and to calibrate because both electrical and mechanical trim may be implemented to calibrate transducer output signals.